some refactoring and bugfixes

src/zutil/ByteUtil.java

@@ -6,7 +6,7 @@ package zutil;
  * Created by Ziver on 2016-01-30.
  */
 public class ByteUtil {
-
+    /** Bitmask array used by utility functions **/
     private static final int[][] BYTE_MASK = new int[][]{
             {0b0000_0001},
             {0b0000_0010, 0b0000_0011},
@@ -18,16 +18,37 @@ public class ByteUtil {
             {0b1000_0000, 0b1100_0000, 0b1110_0000, 0b1111_0000, 0b1111_1000, 0b1111_1100, 0b1111_1110, 0b1111_1111}
     };
 
-    public static byte getBits(byte data, int index, int length){
+    /**
-        length--;
+     * Creates a new subbyte from offset and with a length and shifts the data to the left
-        if(0 > index || index > 7)
+     *
-            throw new IllegalArgumentException("Invalid index argument, allowed value is 0-7");
+     * @param   data    is the byte data
-        if(length < 0 && index-length < 0)
+     * @param   offset   is the bit index, valid values 0-7
-            throw new IllegalArgumentException("Invalid length argument: "+length+", allowed values 1-8 depending on index");
+     * @param   length  is the length of bits to return, valid values 1-8
-
+     * @return a new byte containing a subbyte defined by the offset and length
-        int ret = data & BYTE_MASK[index][length];
+     */
-        ret = ret >>> index-length;
+    public static byte getShiftedBits(byte data, int offset, int length){
+        int ret = 0xFF & getBits(data, offset, length);
+        ret = ret >>> offset+1-length;
         return (byte) ret;
     }
 
+    /**
+     * Creates a new subbyte from offset and with a length
+     *
+     * @param   data    is the byte data
+     * @param   offset   is the bit index, valid values 0-7
+     * @param   length  is the length of bits to return, valid values 1-8
+     * @return a new byte containing a subbyte defined by the offset and length
+     */
+    public static byte getBits(byte data, int offset, int length){
+        length--;
+        if(0 > offset || offset > 7)
+            throw new IllegalArgumentException("Invalid index argument, allowed value is 0-7");
+        if(length < 0 && offset-length < 0)
+            throw new IllegalArgumentException("Invalid length argument: "+length+", allowed values 1-8 depending on index");
+
+        byte ret = (byte) (data & BYTE_MASK[offset][length]);
+        return  ret;
+    }
+
 }

src/zutil/parser/binary/BinaryStructParser.java

@@ -57,7 +57,7 @@ public class BinaryStructParser {
                 int readLength = 0;
                 byte[] valueData = new byte[(int) Math.ceil(length / 8.0)];
                 for (int index = 0; index < valueData.length; ++index) {
-                    valueData[index] = ByteUtil.getBits(data[byteIndex], bitIndex, bitLength);
+                    valueData[index] = ByteUtil.getShiftedBits(data[byteIndex], bitIndex, bitLength);
                     readLength += bitLength;
                     byteIndex++;
                     bitIndex = 7;

test/zutil/test/BinaryStructTest.java

@@ -65,4 +65,22 @@ public class BinaryStructTest {
         BinaryStructParser.parse(struct, "hello world!".getBytes());
         struct.assertObj();
     }
+
+    @Test
+    public void nonLinedLength(){
+        BinaryTestStruct struct = new BinaryTestStruct() {
+            @BinaryField(index=1, length=12)
+            public int i1;
+            @BinaryField(index=2, length=12)
+            public int i2;
+
+            public void assertObj(){
+                assertEquals(17, i1);
+                assertEquals(2048, i2);
+            }
+        };
+
+        BinaryStructParser.parse(struct, new byte[]{0b0000_0001,0b0001_1000,0b0000_0000});
+        struct.assertObj();
+    }
 }

test/zutil/test/ByteUtilTest.java

@@ -12,13 +12,13 @@ public class ByteUtilTest {
 
 
     @Test
-    public void getBits(){
+    public void getShiftedBits(){
-        assertEquals(1, ByteUtil.getBits((byte)0b1000_0000, 7, 1));
+        assertEquals(1, ByteUtil.getShiftedBits((byte)0b1000_0000, 7, 1));
-        assertEquals(1, ByteUtil.getBits((byte)0b0001_0000, 4, 1));
+        assertEquals(1, ByteUtil.getShiftedBits((byte)0b0001_0000, 4, 1));
-        assertEquals(1, ByteUtil.getBits((byte)0b0000_0001, 0, 1));
+        assertEquals(1, ByteUtil.getShiftedBits((byte)0b0000_0001, 0, 1));
 
-        assertEquals(3, ByteUtil.getBits((byte)0b0110_0000, 6, 2));
+        assertEquals(3, ByteUtil.getShiftedBits((byte)0b0110_0000, 6, 2));
 
-        assertEquals((byte)0xFF, ByteUtil.getBits((byte)0b1111_1111, 7, 8));
+        assertEquals((byte)0xFF, ByteUtil.getShiftedBits((byte)0b1111_1111, 7, 8));
     }
 }